Laurdan - Fluorescent Probe
Other groups use fluorescence techniques and ESR to study phase behavior of lipids. These techniques require the use of a minuscule amount of fluorescent probe or spin label, which was thought not to alter membrane phase behavior. Several groups have begun to question this assumption.
We found that 0.05 mol% of the probe DiIC12 is enough to significantly alter the temperature at which the LO and LD phases mix in membranes of 1:1 DOPC:DPPC-D62 + 30% cholesterol (Tmix). In fact, 0.5 mol% DiIC12 raised Tmix by an astonishing 6°C. We are now studying the effects of the probe Laurdan on phase transition temperatures.
Veatch, S.L., Leung, S.S.W., Hancock, B., Thewalt, J. (2007) Fluorescent probes alter miscibility phase boundaries in ternary vesicles. J. Phys. Chem. B. 111:502-504.